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The suprahyoid muscles are a group of four muscles located superior to the hyoid bone in the neck. They include the digastric, mylohyoid, stylohyoid, and geniohyoid muscles. These muscles play an important role in chewing, swallowing, and speech, and are therefore referred to as accessory muscles of mastication. The individual suprahyoid muscles have different embryological origins and are innervated by different nerves. For example, the anterior belly of the digastric muscle is innervated by the mylohyoid nerve, a branch of the mandibular nerve, while the posterior belly is innervated by the facial nerve. The stylohyoid and the posterior belly of the digastric muscle are also innervated by the facial nerve, while the geniohyoid muscle receives its nerve supply from the first cervical nerve via the hypoglossal nerve.
| Characteristics | Values |
|---|---|
| Number of suprahyoid muscles | 4 |
| Types of suprahyoid muscles | Digastric, mylohyoid, stylohyoid, geniohyoid |
| Location | Superior to the hyoid bone |
| Function | Elevate the hyoid bone, coordinate movements of the floor of the mouth, and assist in swallowing, chewing, and vocalization |
| Innervation | Mandibular nerve (CN V3), facial nerve (CN VII), hypoglossal nerve, glossopharyngeal nerve, vagus nerve |
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What You'll Learn
- The digastric muscle is innervated by the mylohyoid nerve and the facial nerve
- The mylohyoid muscle is innervated by the mandibular nerve
- The stylohyoid muscle is innervated by the facial nerve
- The geniohyoid muscle is innervated by the hypoglossal nerve
- The hyoglossus muscle is innervated by the lingual nerve
The digastric muscle is innervated by the mylohyoid nerve and the facial nerve
The digastric muscle is a small, paired suprahyoid muscle located under the jaw. It is comprised of two parts, or bellies, which are separated by an intermediate tendon. The anterior belly is attached to the digastric fossa of the mandible, while the posterior belly is attached to the mastoid notch of the temporal bone. These two bellies unite as the intermediate tendon, which is held in a loop that attaches to the hyoid bone.
The digastric muscle plays a role in various functions, including swallowing, speech, mastication, and breathing. When the hyoid bone is fixed, the digastric muscle acts to depress the mandible, and when the mandible is fixed, it elevates the hyoid bone. This muscle also assists in the extreme opening of the mouth, such as during yawning or taking a large bite.
The suprahyoid muscles, of which the digastric muscle is a part, include the mylohyoid, geniohyoid, stylohyoid, and hyoglossus muscles. These muscles are located superior to the hyoid bone and, together with adjacent tissue, form the floor of the mouth. They work together to position the hyoid bone and coordinate the movements of the mouth floor and hyoid bone during swallowing and vocalization.
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The mylohyoid muscle is innervated by the mandibular nerve
The mylohyoid muscle is a flat, triangular muscle in the neck that forms the floor of the oral cavity of the mouth. It is one of the four suprahyoid muscles, which also include the digastric, geniohyoid, and stylohyoid muscles. The suprahyoid muscles attach to the superior aspect of the hyoid bone and work together to position the hyoid bone and coordinate the movements of the floor of the mouth during swallowing or vocalization.
The mylohyoid muscle is innervated by the mylohyoid nerve, which is a branch of the inferior alveolar nerve. The inferior alveolar nerve, in turn, originates from the mandibular branch of the trigeminal nerve. The trigeminal nerve, also known as CN V, is responsible for the sensory innervation of the face and splits into three main branches: the ophthalmic nerve (CN V1), the maxillary nerve (CN V2), and the mandibular nerve (CN V3). The mandibular nerve provides motor innervation to the muscles involved in mastication, including the mylohyoid muscle.
The mylohyoid nerve provides motor supply to the mylohyoid muscle and can vary in length and path depending on its origin and the nerve's course. Once the mylohyoid nerve reaches the mylohyoid muscle, it branches into several smaller branches to innervate the muscle. The arteries that perfuse the mylohyoid muscle include the mylohyoid branch of the inferior alveolar artery and the submental branches of the facial artery.
The mylohyoid muscle contributes to chewing, speaking, and swallowing. It runs from the mandible to the hyoid bone and is named after its two attachments near the molar teeth. The muscle is derived from embryonic mesoderm, specifically the first pharyngeal arch, which is also the origin of the trigeminal nerve's mandibular branch. This muscle may also be referred to as the diaphragma oris muscle or simply the oral diaphragm, as it separates the submandibular and sublingual spaces in the mouth.
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The stylohyoid muscle is innervated by the facial nerve
The suprahyoid muscles are a group of four muscles located superior to the hyoid bone. They include the digastric, mylohyoid, geniohyoid, and stylohyoid muscles. These muscles function to position the hyoid bone and coordinate the movements of the floor of the mouth and the hyoid bone during swallowing or vocalization.
The stylohyoid muscle is one of the suprahyoid muscles. It originates from the styloid process of the temporal bone and inserts into the hyoid bone. The stylohyoid muscle is innervated by the facial nerve, specifically the stylohyoid branch of the facial nerve (CN VII). This nerve enters the temporal bone at the anterior superior portion of the internal auditory canal, then travels through the mastoid bone in the fallopian canal, exiting the skull base at the stylomastoid foramen. As it exits the stylomastoid foramen, it gives off three motor branches, one of which innervates the stylohyoid muscle.
The stylohyoid muscle is long and slender and assists in elevating the hyoid bone and widening the oesophagus during swallowing. It draws the hyoid bone upwards and backwards, initiating the swallowing process and elongating the floor of the mouth.
The stylohyoid muscle receives arterial supply from branches of the facial artery, posterior auricular artery, and occipital artery. The facial artery is a branch of the external carotid artery and plays an important role in providing blood supply to the suprahyoid region, including the stylohyoid muscle.
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The geniohyoid muscle is innervated by the hypoglossal nerve
The geniohyoid muscle is a short, paired muscle that belongs to the suprahyoid muscle group. The suprahyoid muscles are a group of four muscles located superior to the hyoid bone. They include the digastric, mylohyoid, geniohyoid, and stylohyoid muscles. These muscles work together to position the hyoid bone and coordinate the movements of the floor of the mouth during swallowing or vocalization.
The hypoglossal nerve has been studied as a potential therapeutic target for obstructive sleep apnea (OSA). Electrical stimulation of the hypoglossal nerve has been investigated as a way to compensate for the diminished nocturnal activity of upper airway (UAW) dilators observed in OSA patients. This stimulation has been shown to double the flow of inspired air in humans. However, the inefficiency of this method may be due to the inappropriate placement of electrodes, resulting in the activation of retractor muscles before protruder muscles.
The geniohyoid muscle plays a crucial role in elevating the hyoid bone and moving it anteriorly. This action has consequences for the attached larynx and pharynx, which are also moved anterosuperiorly. By doing so, the geniohyoid muscle assists in deglutition (widening the pharynx to receive food) and voice production. If the hyoid bone is fixed, the geniohyoid muscle helps with mouth opening by depressing the mandible and pulling it inwards.
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The hyoglossus muscle is innervated by the lingual nerve
The hyoglossus muscle is a thin, quadrilaterally shaped extrinsic muscle of the tongue. It originates from the hyoid bone and inserts onto the side of the tongue. The hyoglossus muscle is innervated by the hypoglossal nerve, also known as cranial nerve XII. This nerve controls the movement of the tongue, allowing it to make different shapes and noises, such as clicking sounds. It also aids in swallowing and moving substances around in the mouth.
The hypoglossal nerve is one of the 12 paired cranial nerves. It starts at the base of the brain near the top of the spinal cord (brainstem) and travels down the neck, branching out and ending at the base and underside of the tongue. The hypoglossal nerve controls the hyoglossus, intrinsic, genioglossus, and styloglossus muscles. These muscles work together to enable tongue movement and perform various functions, such as pushing the tongue forward or pulling it back and flattening it.
The hyoglossus muscle plays a crucial role in tongue movement and speech. By depressing and retracting the tongue, it helps to form words and sounds. Additionally, the hyoglossus muscle is involved in swallowing and moving substances within the mouth. This muscle works in coordination with other muscles controlled by the hypoglossal nerve to facilitate these functions.
The hyoglossus muscle is positioned in the upper neck and the floor of the mouth. Its fibres pass almost vertically upward to enter the side of the tongue, inserting between the styloglossus and the inferior longitudinal muscle. Several important structures are located laterally between the hyoglossus and mylohyoid muscles, including the sublingual gland, submandibular duct, lingual nerve, vena comitans of the hypoglossal nerve, and the hypoglossal nerve itself.
The hyoglossus muscle is susceptible to various health conditions that can affect its function. For example, in advanced cases of amyotrophic lateral sclerosis (ALS), the hypoglossal nerve may struggle to communicate with the brain. Encephalitis, an inflammation of the brain, can also impact the hyoglossus muscle by causing pressure on the hypoglossal nerve. Additionally, head and neck cancer treatments can disrupt nearby tissue, including the hypoglossal nerve, potentially affecting the muscle's function.
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Frequently asked questions
The suprahyoid muscles are a group of four muscles located superior to the hyoid bone. They include the digastric, mylohyoid, geniohyoid, and stylohyoid muscles.
The suprahyoid muscles contribute to the floor of the mouth and play a role in chewing, swallowing, and speech. They also assist in elevating the hyoid bone and widening the oesophagus during swallowing.
The innervation of the suprahyoid muscles depends on their specific muscle bellies. The anterior belly of the digastric muscle is innervated by the mylohyoid nerve, a branch of the mandibular nerve (CN V3). The posterior belly of the digastric and the stylohyoid muscles are innervated by the facial nerve (CN VII). The geniohyoid muscle is innervated by the hypoglossal nerve (CN XII).
